This is the latest book in the Joe Pickett series. It has a wide range of characters-- from a group of assassins known as the Wolf Pack, to local law enforcement and federal agents and drugs and witnesses. The assassins have been gathered together for several specific murders. They are very efficient and range from Arizona to Wyoming with bodies along their path. A final gunfight is followed by an appropriate ending.
Another C.J. Box winner, and well worth reading.
It's been out about ten days at this time and should be available online and at a local bookstore.
